TW201409779A - Wiring board, light-emitting device and method for manufacturing wiring board - Google Patents

Abstract

This invention provides a wiring board, a light-emitting device and a method for manufacturing wiring board which can inhibit decline of reflectivity of light and improve the reliability associated with bonding. A wiring board of an embodiment includes a base part being a plate shape; a wiring disposed on a surface of the base part and disposed at a position which is distant from the circumference of the base part; a first metal layer disposed at a side of the wiring opposite to a side of the base part; and a second metal layer covering the first metal layer and a sidewall of the wiring.

Description

Wiring substrate, light emitting device, and method of manufacturing wiring substrate

The embodiment to be described later generally relates to a wiring board, a light-emitting device, and a method of manufacturing the wiring board.

There is a chip on board (COB) type light-emitting device in which a light-emitting diode is directly mounted on a substrate. In a COB (Chip On Board) type light-emitting device, wiring or electrodes in which a plurality of metal layers are laminated are provided on a plate-like base portion in order to prevent corrosion of wiring and improve bonding at the time of soldering. Such wiring or electrodes are formed using electroplating or electroless plating. However, if a plurality of metal layers are laminated by electroplating, there is a case where the side walls of the lower metal layer are exposed. When the side wall of the lower metal layer is exposed, there is a case where the metal layer of the lower layer is corroded by oxidation, vulcanization, or the like, and the reflectance of light incident on the side wall may be lowered by corrosion of the side wall. On the other hand, when a plurality of metal layers are laminated by electroless plating, a metal layer having a reducing agent component contained in the plating solution is formed. In this case, since the concentrated portion of the reducing agent component is generated at the time of solder bonding, the reliability of solder bonding may be lowered.

A problem to be solved by the present invention is to provide a wiring board, a light-emitting device, and a method of manufacturing a wiring board which can suppress a decrease in reflectance of light and improve reliability in connection.

A wiring board according to an embodiment includes: a base portion having a flat shape; a wiring disposed on one surface of the base portion and disposed at a position away from a periphery of the base portion; and a first metal layer disposed at the wiring portion a side opposite to one side of the base; and a second metal layer covering the first metal layer and the sidewall of the wiring.

According to an embodiment, in the wiring substrate, a solder portion containing at least tin is included on the second metal layer, and an activation energy required to mutually diffuse the material of the first metal layer and tin is, for example, higher than a material for wiring The activation energy required for the mutual diffusion of tin.

According to an embodiment, in the wiring substrate, the ionization energy of the material of the second metal layer is, for example, higher than the ionization energy of the material of the wiring and the material of the first metal layer.

According to an embodiment, in the wiring substrate, the thickness dimension of the first metal layer is, for example, greater than the thickness dimension of the second metal layer.

According to an embodiment, in the wiring substrate, the first metal layer substantially does not contain phosphorus, for example.

According to an embodiment, in the wiring substrate, the thickness of the first metal layer is, for example, 0.003 mm or more and 0.1 mm or less.

According to an embodiment, in the wiring substrate, the thickness of the second metal layer is, for example, 0.0001 mm or more and 0.0003 mm or less.

According to an embodiment, in the wiring substrate, the first metal layer comprises nickel and palladium At least one element.

According to an embodiment, in the wiring substrate, the first metal layer includes a plurality of layers laminated.

According to an embodiment, the wiring substrate further includes: a third metal layer disposed on a side of the base opposite to a side on which the wiring is disposed; and a fourth metal layer disposed on the base of the third metal layer and the base a side opposite to the side; and a fifth metal layer covering the sidewalls of the fourth metal layer and the third metal layer.

According to an embodiment, in the wiring substrate, the material of the wiring is, for example, the same as the material of the third metal layer, and the material of the first metal layer is, for example, the same as the material of the fourth metal layer, and the material of the second metal layer is, for example, The material of the fifth metal layer is the same.

According to an embodiment, in the wiring substrate, the base is formed of, for example, ceramic or a composite ceramic containing ceramic and resin.

A light emitting device of an embodiment includes: the wiring substrate; a light emitting element disposed on a side of the second metal layer opposite to a side on which the first metal layer is disposed; and a solder portion disposed on the light emitting element and the second metal layer between.

A method of manufacturing a wiring substrate of an embodiment includes the steps of: forming a first seed layer on one side of a base; forming a first resist mask on the first seed layer; and forming a first resist mask on the first resist mask An opening portion, and a wiring and a first metal layer are sequentially formed at a position away from a periphery of the base; the first resist mask and the remaining first seed layer are removed; and the first metal layer and the wiring are formed a second metal layer covered by the sidewalls.

According to an embodiment, in the method of manufacturing a wiring substrate, in the step of forming the first seed layer on one side of the base, the side of the base opposite to the side on which the first seed layer is formed is opposed a second seed layer may be further formed on the surface of one side; and in the step of forming a first resist mask on the first seed layer, a second resist may be further formed on the second seed layer a mask in the opening portion of the first resist mask and at a position away from the periphery of the base, in the step of sequentially forming the wiring and the first metal layer, in the opening portion of the second resist mask, And at a position away from the periphery of the base, the third metal layer and the fourth metal layer may be sequentially formed; in the step of removing the first resist mask and the remaining first seed layer, the The second resist mask is removed from the remaining second seed layer; in the step of forming the second metal layer covering the first metal layer and the sidewall of the wiring, the fourth metal layer and the third layer may be further formed A fifth metal layer covered by the sidewalls of the metal layer.

According to the embodiment of the present invention, it is possible to provide a wiring board, a light-emitting device, and a method of manufacturing a wiring board which can suppress a decrease in reflectance of light and improve reliability in connection.

1‧‧‧Wiring substrate

2. Base of 302‧‧‧

3, 303‧‧‧ wiring department

3a, 303a‧‧‧ wiring

3a1, 4a1, 303a1‧‧‧ side walls

3b, 303b‧‧‧ first metal layer

3b1, 3b2, 3c1, 3c2, 4b1, 4b2, 4c1, 4c2, 101b‧ ‧ layers

3c, 303c‧‧‧ second metal layer

4‧‧‧ joints

4a‧‧‧ third metal layer

4b‧‧‧fourth metal layer

4c‧‧‧ fifth metal layer

5‧‧‧ solder department

11a‧‧‧First seed layer

11b‧‧‧Second seed layer

14a‧‧‧First resist mask

14b‧‧‧second resist mask

100‧‧‧Lighting device

101‧‧‧Lighting elements

101a‧‧‧ single crystal substrate

101c‧‧‧Bumps

102‧‧‧wavelength conversion unit

103‧‧‧ Sealing Department

200‧‧‧ components

205‧‧‧ solder

301‧‧‧ seed layer

304‧‧‧resist mask

Part A‧‧‧

1(a) to 1(d) are schematic views for illustrating a light-emitting device 100 including the wiring substrate 1 of the first embodiment, and FIG. 1(a) is a perspective view of the light-emitting device 100, and FIG. 1(b) 1(a) is a top view of FIG. 1(a), and FIG. 1(d) is a cross-sectional view of FIG. 1(a).

2(a) to 2(c) are schematic views for illustrating the wiring board 1. Fig. 2(a) is an enlarged cross-sectional view of a portion A in Fig. 1(d), and Fig. 2(b) is An exemplary cross-sectional view is illustrated for a first metal layer and a fourth metal layer having a plurality of layers, and FIG. 2(c) is a second metal layer and a fifth metal layer having a plurality of layers laminated. An exemplary cross-sectional view.

3(a) to 3(d) are schematic cross-sectional views illustrating a method of manufacturing the wiring substrate 300 of the comparative example.

4(a) to 4(e) are schematic cross-sectional views showing a method for manufacturing the wiring board 1 of the second embodiment.

A first invention is a wiring substrate comprising: a base having a flat shape; a wiring disposed on one surface of the base and disposed at a position away from a circumference of the base; a first metal layer disposed at the a side of the wiring opposite to a side of the base; and a second metal layer covering the first metal layer and a sidewall of the wiring.

A second metal layer covering the side walls is provided on the wiring substrate, and the side walls are exposed portions of the wiring. Therefore, it is possible to suppress a decrease in the reflectance of light, and it is possible to suppress a decrease in light emission efficiency.

Further, according to the first invention, the second invention is a wiring substrate including a solder portion containing at least tin on the second metal layer, and a material for diffusing the material of the first metal layer and tin The activation energy is higher than the activation energy required to interdif the material of the wiring with tin. That is, the speed at which the material of the first metal layer and the tin are mutually diffused is slower than the speed at which the material of the wiring and the tin diffuse.

According to the wiring substrate, when the light emitting element is soldered, An alloy layer is formed between the material of the first metal layer and the tin, but the alloy layer formed is an alloy layer having a strength higher than that of the material of the wiring and the alloy layer formed of tin. Moreover, since the speed at which the material of the first metal layer and the tin are mutually diffused is slow, it is possible to suppress an increase in the thickness dimension of the alloy layer. Therefore, the reliability of bonding at the time of joining the light-emitting elements can be improved.

Further, according to the first invention or the second invention, the third invention is a wiring substrate, wherein a material of the second metal layer has a higher ionization energy than a material of the wiring and a material of the first metal layer Ionization energy.

According to the wiring board, it is possible to suppress oxidation or vulcanization of the side wall, that is, the exposed portion of the wiring. As a result, it is possible to suppress corrosion of the wiring, and therefore, it is possible to suppress a decrease in the reflectance of light, and it is possible to suppress a decrease in light emission efficiency.

Further, according to any one of the first to third inventions, the fourth invention is a wiring substrate, wherein a thickness dimension of the first metal layer is larger than a thickness dimension of the second metal layer.

Further, a fifth invention is the light-emitting device, comprising: the wiring substrate according to any one of the first to fourth inventions; the light-emitting element provided on the second metal layer and provided with the first metal layer One side opposite to the other side; and a solder portion disposed between the light emitting element and the second metal layer.

Since the wiring board is included in the light-emitting device, the light emission efficiency can be improved, and reliability relating to bonding of a light-emitting element or the like can be improved.

Further, a sixth invention is a method of manufacturing a wiring substrate, comprising the steps of: forming a first seed layer on one side of a base; Forming a first resist mask on the first seed layer; forming a wiring and a portion in the opening portion of the first resist mask at a position away from the periphery of the base a metal layer; removing the first resist mask and the remaining first seed layer; and forming a second metal layer, the second metal layer and the wiring The side walls are covered.

According to the method for manufacturing a wiring board, since the reducing agent component is not contained in the first metal layer, when the light emitting element is soldered, generation of a reducing agent component (for example, when the first metal layer is made of nickel) can be suppressed. Concentrated part of phosphorus, etc.). As a result, the reliability associated with the joint can be improved.

Further, even if the wiring of the wiring board is not formed to the end portion of the base portion, the exposed portion of the wiring, that is, the side wall, can be covered by the second metal layer. Therefore, it is possible to suppress a decrease in the reflectance of light, and it is possible to suppress a decrease in light emission efficiency.

Hereinafter, an embodiment will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and the detailed description is omitted as appropriate.

[First Embodiment]

1(a) to 1(d) are schematic views for illustrating a light-emitting device 100 including the wiring substrate 1 of the first embodiment.

1(a) is a perspective view of the light-emitting device 100, FIG. 1(b) is a plan view of FIG. 1(a), FIG. 1(c) is a bottom view of FIG. 1(a), and FIG. 1(d) is a view Figure 1 (a) is a cross-sectional view.

2(a) to 2(c) are diagrams for illustrating the wiring substrate 1 Figure.

2(a) is an enlarged cross-sectional view of a portion A in FIG. 1(d), and FIG. 2(b) is a cross-sectional view showing an example of a first metal layer and a fourth metal layer in which a plurality of layers are laminated. 2(c) is a cross-sectional view showing an example of a second metal layer and a fifth metal layer in which a plurality of layers are laminated.

As shown in FIGS. 1(a) to 1(d), the light-emitting device 100 is provided with a wiring board 1, a light-emitting element 101, a wavelength conversion unit 102, and a sealing portion 103.

The wiring board 1 is provided with a base portion 2, a wiring portion 3, and a joint portion 4.

The details related to the wiring substrate 1 will be described later.

The light emitting element 101 is disposed on a side of the second metal layer 3c opposite to the side on which the first metal layer 3b is provided.

The light-emitting element 101 can be, for example, a light-emitting element such as a light-emitting diode, an organic light-emitting diode, or a laser diode.

The light-emitting element 101 can be, for example, a blue light-emitting diode that emits blue light.

When the light-emitting element 101 is a blue light-emitting diode, as shown in FIG. 2(a), a GaN-based nitride can be formed on a single crystal substrate 101a having good lattice matching properties such as sapphire. Layer 101b of the semiconductor.

The light-emitting element 101 is connected (flip chip mounted) to the wiring portion 3 via a bump (protrusion) 101c provided on the layer 101b side. However, the light-emitting element 101 need not be a flip-chip type light-emitting element, and may be a light-emitting element of the type (wire bonding method) in which light-emitting elements of the type (wire bonding method) are formed on the upper surface. Layer and use wire to The component and the wiring are electrically joined. When the light-emitting element 101 mounted on the flip chip is used, the mounting area can be reduced as compared with the light-emitting element connected by the wire bonding method. Further, since the distance between the light-emitting element 101 and the wiring portion 3 can be shortened, electrical characteristics can be improved.

Further, as shown in FIG. 2(a), the layer 101b including the light-emitting layer is provided on the wiring substrate 1 side. Since the layer 101b including the light-emitting layer serves as a heat source, it is easy to dissipate heat to the wiring board 1 side.

Further, in the case of a light-emitting element that is connected by a wire bonding method, an electrode for wiring is provided on the light-emitting side, and thus light emission efficiency may be deteriorated. On the other hand, when the light-emitting element 101 mounted on the flip-chip is provided, there is no obstruction on the light-emitting side, and therefore the light-emitting efficiency can be improved.

The wavelength conversion unit 102 is provided to cover a plurality of light-emitting elements 101. The wavelength conversion unit 102 includes a phosphor that is excited by primary light emitted from the light-emitting element 101.

The wavelength conversion unit 102 can be, for example, a portion in which a particulate phosphor is dispersed in a translucent organic or inorganic material. Examples of the light-transmitting organic substance include an epoxy resin, a silicone resin, a methacrylic resin (Polymethyl Methacrylate (PMMA)), and a polycarbonate (Polycarbonate). , PC), Cycloolefin Polymer (COP), alicyclic acrylic acid (OZ), Allyl Diglycol Carbonate (ADC), acrylic resin, fluorine resin, anthrone a hybrid resin of a resin and an epoxy resin, and A urethane resin or the like. In addition, as the inorganic substance having light transmissivity, for example, glass or the like can be exemplified.

The organic substance having light transmissivity is preferably a resin having thixotropic properties and having a Shore hardness of D40 or more after curing. When such a resin is used, it is easy to make the shape of the wavelength conversion part 102 into a desired shape. Further, since deformation due to an external force can be suppressed, the reliability of the connection between the light-emitting element 101 and the wiring portion 3 can be improved. However, as long as the desired shape and characteristics can be ensured, the Shore hardness of the resin is not limited to the aforementioned Shore hardness, and a resin having a Shore hardness of D40 or less may be used.

Further, among the materials of the wavelength conversion unit 102, it is preferable to use a resin material whose resin ligand is not easily broken by blue light having high energy. By using such a resin, coloring caused by breakage of the resin structure at the time of lighting for a long period of time can be suppressed, and therefore long-term reliability of the light-emitting characteristics can be ensured. Although an fluorenone resin is mainly used as the resin having the above-described characteristics, there is a problem that since the gas permeability is high, the outside air permeates into the inside of the wavelength conversion portion 102, and the elements covered by the wavelength conversion portion 102 are deteriorated. Therefore, it is necessary to make the wavelength conversion portion 102 have a structure resistant to gas corrosion.

The phosphor contained in the wavelength conversion unit 102 can be, for example, a YAG phosphor (yttrium-aluminum-garnet phosphor). When the light-emitting element 101 is a blue light-emitting diode and the phosphor included in the wavelength conversion unit 102 is a YAG phosphor, the YAG phosphor is excited by the blue light emitted from the light-emitting element 101. Yellow fluorescent light is emitted from the YAG phosphor. Then, the blue light is mixed with the yellow light, whereby white Light is emitted from the light emitting device 100. In addition, the phosphor is not limited to the YAG phosphor, and can be appropriately changed in accordance with the use of the light-emitting device 100 or the like to obtain a desired luminescent color.

The sealing portion 103 is provided to cover the wavelength conversion portion 102.

The sealing portion 103 is disposed at a position away from the circumference of the base 2 . That is, the sealing portion 103 does not reach the end portion (peripheral edge) of the base portion 2.

The sealing portion 103 is formed of an organic or inorganic substance having light transmissivity.

The sealing portion 103 can be formed, for example, of a resin having light transmissivity. Examples of the light-transmitting resin include an epoxy resin, an anthrone-based resin, a methacrylic resin (PMMA), a polycarbonate (PC), a cycloolefin polymer (COP), and an alicyclic acrylic acid (OZ). Allyl diethylene glycol carbonate (ADC), an acrylic resin, a fluorine-based resin, a mixed resin of an anthrone-based resin and an epoxy resin, and a polyurethane resin.

In this case, the value of the refractive index of the resin forming the sealing portion 103 is preferably equal to or lower than the value of the refractive index of the resin forming the wavelength converting portion 102. That is, the value of the refractive index of the sealing portion 103 is preferably equal to or less than the value of the refractive index of the wavelength conversion portion 102.

When the sealing portion 103 having the refractive index as described above is used, it is possible to suppress the light incident on the sealing portion 103 from returning to the wavelength conversion portion 102. In addition, when the value of the refractive index of the resin forming the sealing portion 103 is equal to the value of the refractive index of the resin forming the wavelength conversion portion 102, it is possible to suppress the interface between the sealing portion 103 and the wavelength conversion portion 102. reflection. For example, the sealing portion 103 may be formed of the same resin. And the wavelength conversion unit 102. However, depending on the characteristics of the wavelength conversion portion 102, the sealing portion 103 may or may not be available.

Next, the wiring board 1 will be described.

The planar shape of the base 2 has a rectangular flat shape.

The base 2 is preferably formed of a material having insulating properties, small thermal expansion, and excellent heat dissipation and heat resistance. The base 2 may be formed of, for example, ceramics, a composite ceramic of ceramics and resin, or the like. Examples of the ceramics include alumina (Al ₂ O ₃ ), aluminum nitride (AlN), beryllium oxide (BeO), talatite (MgO.SiO ₂ ), zircon (ZrSiO ₄ ), and tantalum nitride. (Si ₃ N ₄ ) and the like.

The thickness of the base portion 2 is not particularly limited. However, in consideration of rigidity, heat dissipation, and the like, for example, it is preferably 0.3 mm or more and 3 mm or less.

However, it is not limited to the shape, material, and thickness dimension which have been illustrated, and can be suitably changed.

As shown in FIG. 1(b), the wiring portion 3 is provided on one surface of the base portion 2, and is disposed at a position away from the periphery of the base portion 2. That is, the wiring portion 3 does not reach the end portion (peripheral edge) of the base portion 2.

As shown in FIG. 2(a), the wiring portion 3 is provided with a wiring 3a, a first metal layer 3b, and a second metal layer 3c.

The wiring 3a is provided on one face of the base 2. The wiring 3a is disposed at a position away from the circumference of the base 2. The wiring 3a is provided in order to supply electric power to the light emitting element 101. Therefore, the wiring 3a is formed of a material having conductivity. As the material having conductivity, for example, copper (Cu) or the like can be exemplified. Furthermore, the method of forming the wiring 3a will be Said.

The first metal layer 3b is provided on a surface of the wiring 3a on the side opposite to one side of the base 2. The first metal layer 3b is provided to suppress formation of an alloy between the tin (Sn) contained in the solder and the wiring 3a when the light-emitting element 101 is soldered. For example, when the light-emitting element 101 is soldered, an alloy (Cu-Sn alloy) of tin contained in the solder and copper of the wiring 3a is formed. In this case, the first metal layer 3b is not present in a general device, and even if there is only copper, there is no problem, but for a light source device (light-emitting device) which particularly requires long-term reliability, a brittle alloy layer ( The growth of, for example, Cu-Sn alloys can be problematic. Therefore, it is preferable to select the material of the first metal layer 3b so that the speed at which the material of the first metal layer 3b and the tin are mutually diffused is slower than the speed at which the copper and tin are mutually diffused.

Therefore, for the material of the first metal layer 3b, the activation energy required to mutually diffuse the material of the first metal layer 3b and tin is higher than the activation energy required to mutually diffuse the material of the wiring 3a and tin. That is, with respect to the material of the first metal layer 3b, the speed at which the material of the first metal layer 3b and the tin are mutually diffused is slower than the speed at which the material of the wiring 3a and the tin mutually diffuse.

As a material of the first metal layer 3b, for example, nickel (Ni), palladium (Pd), or the like can be exemplified. Further, the first metal layer 3b may be formed as one layer, or may be a layer in which a plurality of layers are laminated. For example, as shown in FIG. 2(b), the first metal layer 3b in which the layer 3b1 and the layer 3b2 are laminated may be used. Furthermore, the number of layers is not limited to the number that has been exemplified. In the case where the first metal layer 3b having a plurality of layers is laminated, a layer formed of nickel and a layer formed of palladium may be included. That is, the first metal layer 3b may include at least at least nickel and palladium. Any one element.

Further, when the first metal layer 3b is formed, a different element may be contained in the first metal layer 3b according to the formation method. As an example, a reducing agent component used for electroless plating is mentioned. For example, there is phosphorus (P) or the like contained in a reducing agent for electroless nickel plating. When phosphorus is contained, when the light-emitting element 101 is welded, the concentration of phosphorus locally increases, and a decrease in bonding strength due to the concentrated portion of phosphorus or the like occurs. Therefore, the reliability of the joint when the light-emitting element 101 is joined may be lowered. Therefore, the first metal layer 3b does not substantially contain a different element. Further, the content in which the first metal layer 3b does not substantially contain the heterogeneous element will be described later.

The second metal layer 3c is provided to cover the first metal layer 3b and the exposed portion of the wiring 3a, that is, the side wall 3a1.

Here, when the first metal layer 3b is oxidized, there are problems such as solder wettability during soldering of the light-emitting element 101 and upward spread of the remaining solder accompanying the solder wettability, which may cause leakage ( Leak) and other bad.

In addition, a part of the primary light from the light-emitting element 101 or the fluorescent light emitted from the phosphor contained in the wavelength conversion unit 102 is a boundary surface of the wavelength conversion unit 102 and the sealing portion 103, or a sealing portion. The boundary surface between the 103 and the outside air is reflected, and then incident on the side wall 3a1 of the wiring 3a.

In this case, when the side wall 3a1 of the wiring 3a is corroded, the reflectance of light incident on the side wall 3a1 is lowered, and the light emission efficiency may be lowered.

Therefore, the second metal layer 3c is provided to suppress the first metal layer 3b and the wiring The side wall 3a1 of 3a is corroded.

In order to suppress oxidation of the first metal layer 3b and the side wall 3a1 of the wiring 3a, the ionization energy of the material of the second metal layer 3c is higher than the ionization energy of the material of the first metal layer 3b and the ionization energy of the material of the wiring 3a.

As a material of the second metal layer 3c, for example, gold (Au), palladium, or the like can be exemplified.

Further, the second metal layer 3c may be formed as one layer, or may be a layer in which a plurality of layers are laminated. For example, as shown in FIG. 2(c), the second metal layer 3c in which the layer 3c1 and the layer 3c2 are laminated may be used. Furthermore, the number of layers is not limited to the number that has been exemplified. In the case where the second metal layer 3c having a plurality of layers is laminated, a layer formed of gold and a layer formed of palladium may be contained. That is, the second metal layer 3c may contain at least one of gold and palladium.

The solder portion 5 is provided between the light emitting element 101 and the second metal layer 3c.

The solder portion 5 may be formed by soldering using solder as a base and containing at least gold, silver, copper, bismuth, nickel, indium, zinc, antimony, bismuth, and antimony. Any one or more of the elements.

When the light-emitting element 101 is soldered, there is a case where the second metal layer 3c located directly under the solder portion 5 disappears.

Further, there is a case where an alloy layer is formed between the solder portion 5 and the second metal layer 3c, and the alloy layer includes the metal contained in the solder portion 5 and the second metal layer 3c.

In addition, there is a case where, when the second metal layer 3c located directly under the solder portion 5 disappears, a formation is formed between the solder portion 5 and the first metal layer 3b. An alloy layer containing the metal contained in the solder portion 5 and the first metal layer 3b.

In the flip chip type bonding process, there is a case where the clearance between the electrodes is narrow, and the solder may overflow from the electrode during soldering, and therefore, there is a short circuit between the electrodes. The problem. When the wiring 3a and the first metal layer 3b are covered by the second metal layer 3c, the solder easily adheres to the side wall 3a1 side of the wiring 3a, so that short-circuit between the electrodes can be suppressed.

The thickness dimension of the wiring 3a may be larger than the thickness dimension of the first metal layer 3b. The thickness dimension of the first metal layer 3b may be greater than the thickness dimension of the second metal layer 3c.

In this case, when the wiring 3a is formed in consideration of conductivity or by a plating method to be described later, the thickness of the wiring 3a is preferably 0.02 mm or more and 0.3 mm or less.

The lower limit of the thickness dimension of the first metal layer 3b can be set to be equal to or greater than the thickness dimension which does not disappear due to the diffusion of tin in the range of the life required for the product. Further, from the viewpoint of suppressing cost, it is preferable to form a film without excessive thickness. Therefore, the thickness dimension of the first metal layer 3b is preferably set to 0.003 mm or more and 0.1 mm or less.

The thickness of the second metal layer 3c may be a thickness dimension that can reliably cover the surface layer of the wiring 3a from the viewpoint of exerting the function of the second metal layer 3c. Therefore, the thickness dimension of the second metal layer 3c is preferably set to 0.0001 mm or more and 0.0003 mm or less.

The third metal layer 4a, the fourth metal layer 4b, and the fifth metal layer 4c are provided in the joint portion 4.

The joint portion 4 is provided to weld the wiring substrate 1 to other members 200 (for example) Such as a heat spreader (heat spreader, etc.). Therefore, the joint portion 4 is not necessarily required, and the joint portion 4 can be appropriately provided as needed.

The third metal layer 4a is provided on the side of the base 2 opposite to the side on which the wiring portion 3 is provided. The third metal layer 4a is disposed at a position away from the circumference of the base 2. However, the third metal layer 4a is provided to cover the surface of the base 2.

The fourth metal layer 4b is provided on a surface of the third metal layer 4a opposite to one side of the base 2. The fourth metal layer 4b is provided to suppress formation of an alloy between the tin contained in the solder 205 and the third metal layer 4a when the wiring board 1 is soldered to the other member 200.

The fourth metal layer 4b may be one layer or a layer in which a plurality of layers are laminated. For example, as shown in FIG. 2(b), the fourth metal layer 4b in which the layer 4b1 and the layer 4b2 are laminated may be used. Furthermore, the number of layers is not limited to the number that has been exemplified.

The fifth metal layer 4c is provided to cover the fourth metal layer 4b and the exposed portion of the third metal layer 4a, that is, the side wall 4a1. Further, as shown in FIG. 2(c), a fifth metal layer 4c in which the layer 4c1 and the layer 4c2 are laminated may be used. Furthermore, the number of layers is not limited to the number that has been exemplified. In the case where the fifth metal layer 4c having a plurality of layers is laminated, a layer formed of gold and a layer formed of palladium may be contained. That is, the fifth metal layer 4c may contain at least one of gold and palladium.

Here, the material or thickness dimension of the third metal layer 4a, the fourth metal layer 4b, and the fifth metal layer 4c is not particularly limited, but other members 200 are welded in addition to the joint portion 4, and thus, Similarly, the wiring portion 3 must take into consideration the reliability of bonding or the like. In addition, productivity can be achieved as long as the wiring portion 3 and the joint portion 4 can be simultaneously formed. improve.

Therefore, the material or thickness dimension of the third metal layer 4a may be the same as the material or thickness dimension of the wiring 3a.

In addition, the material or thickness dimension of the fourth metal layer 4b may be the same as the material or thickness dimension of the first metal layer 3b.

In addition, the material or thickness dimension of the fifth metal layer 4c may be the same as the material or thickness dimension of the second metal layer 3c.

In this way, the reliability and the like of the joint of the joint portion 4 can be improved, and the productivity can be improved.

As in the case of the material of the solder portion 5, solder may be used as the solder 205, which is based on tin and contains at least gold, silver, copper, bismuth, nickel, indium, zinc, bismuth, antimony, and bismuth. As the solder 205, solder which can be bonded at a lower temperature can also be used as the element or more.

In the wiring board 1 and the light-emitting device 100 of the present embodiment, the second metal layer 3c is provided, and the second metal layer 3c covers the exposed portion of the wiring 3a, that is, the side wall 3a1. Therefore, it is possible to suppress the side wall 3a1 from being corroded by oxidation, vulcanization or the like. As a result, it is possible to suppress a decrease in the reflectance of light, and it is possible to suppress a decrease in the light emission efficiency.

Further, since the dissimilar elements as the reducing agent component are not substantially contained in the first metal layer 3b, it is possible to suppress the formation of the enriched portion of the reducing agent component when the light-emitting element 101 is welded. As a result, the reliability associated with the joint can be improved.

Further, a fifth metal layer 4c is provided which covers the exposed portion of the third metal layer 4a, that is, the side wall 4a1. Therefore, the side wall 4a1 can be suppressed Oxidation. As a result, corrosion of the third metal layer 4a can be suppressed, so that the reliability of bonding of the third metal layer 4a and the base 2 can be improved.

Further, since the fourth metal layer 4b does not substantially contain the different element as the reducing agent component, it is possible to suppress the formation of the concentrated portion of the reducing agent component when the other member 200 is welded. As a result, the reliability associated with the joint can be improved.

[Second Embodiment]

Before the method of manufacturing the wiring board 1 of the second embodiment is exemplified, a method of manufacturing the wiring board 300 of the comparative example will be described.

3(a) to 3(d) are schematic cross-sectional views illustrating a method of manufacturing the wiring substrate 300 of the comparative example.

In the method of manufacturing the wiring substrate 300 of the comparative example, the wiring portion 303 is formed at a position away from the peripheral end of the base portion 302 by using a plating method.

First, as shown in FIG. 3(a), a seed layer 301 containing a conductive material is formed on one surface of the base portion 302.

Next, as shown in FIG. 3(b), a resist mask 304 is formed on the seed layer 301.

Next, as shown in FIG. 3(c), the wiring 303a, the first metal layer 303b, and the second metal layer 303c are sequentially formed by an electroplating method. At this time, the seed layer 301 containing the conductive material reaches the peripheral end of the base portion 302, and therefore, a current can be applied from the peripheral end of the base portion 302. Therefore, the wiring 303a, the first metal layer 303b, and the second metal layer 303c can be sequentially formed at a position away from the peripheral end of the base portion 302.

Next, as shown in FIG. 3(d), the resist mask 304 and the remaining crystals are used. The seed layer 301 is removed. In this manner, the wiring portion 303 can be formed at a position away from the peripheral end of the base portion 302.

However, when the wiring portion 303 is formed at a position away from the peripheral end of the base portion 302 by the plating method, the side wall 303a1 of the wiring 303a is exposed. As described above, when the side wall 303a1 of the wiring 303a is exposed, the side wall 303a1 is corroded, the reflectance of light may be lowered, and the light emission efficiency may be lowered.

In this case, the wiring 303a, the first metal layer 303b, and the second metal layer 303c may be sequentially formed at a position away from the peripheral end of the base portion 302 by electroless plating. In this case, the side wall 303a1 of the wiring 303a can be covered by the first metal layer 303b and the second metal layer 303c.

Here, as described above, the activation energy required to mutually diffuse the material of the first metal layer 303b and tin is higher than the activation energy required to mutually diffuse the material of the wiring 303a and tin, and is not easily diffused. For example, the material of the first metal layer 303b is nickel.

In the case where the first metal layer 303b containing nickel is formed using an electroless plating method, hypophosphorous acid (H ₃ PO ₂ ) may be used as a reducing agent. Therefore, phosphorus is contained in the first metal layer 303b.

As described above, if phosphorus is contained in the first metal layer 303b, there is a case where the concentration of phosphorus locally increases when the light-emitting element 101 is soldered. Since a decrease in bonding strength due to the concentrated portion of the phosphorus or the like occurs, a new problem arises in that the reliability of bonding when the light-emitting element 101 is bonded is lowered.

Therefore, in the method of manufacturing the wiring substrate 1 of the second embodiment, the root The wiring portion 3 is formed in the following order.

4(a) to 4(e) are schematic cross-sectional views showing a method for manufacturing the wiring board 1 of the second embodiment.

4(a) to 4(e) show the case where the wiring portion 3 and the joint portion 4 are simultaneously formed.

In the method of manufacturing the wiring substrate 1 of the second embodiment, the wiring 3a and the first metal layer 3b, and the third metal layer 4a and the fourth metal layer 4b are formed at a position away from the peripheral end of the base 2 by a plating method. Next, the second metal layer 3c is formed by covering the wiring 3a and the first metal layer 3b by electroless plating, and the third metal layer 4a and the fourth metal layer 4b are covered. Five metal layers 4c.

First, as shown in FIG. 4(a), a first seed layer 11a is formed on one surface of the base 2. Further, a second seed layer 11b is formed on the side of the base 2 opposite to the side on which the first seed layer 11a is formed.

The first seed layer 11a and the second seed layer 11b are formed to impart conductivity to the surface of the insulating base 2. The conductive material is not particularly limited, and for example, it can be made of the same material as the wiring 3a. The conductive material can be, for example, copper.

For example, the first seed layer 11a and the second seed layer 11b may be formed using a sputtering method. The thickness of the first seed layer 11a and the second seed layer 11b can be, for example, about 0.00005 mm.

Next, as shown in FIG. 4(b), a first resist mask 14a is formed on the first seed layer 11a. In addition, a second resist mask is formed on the second seed layer 11b. 14b.

The first resist mask 14a is for forming the wiring 3a and the first metal layer 3b at a predetermined position on the first seed layer 11a.

The second resist mask 14b is for forming the third metal layer 4a and the fourth metal layer 4b at predetermined positions on the second seed layer 11b.

For example, a liquid resist is uniformly applied to the first seed layer 11a and the second seed layer 11b by using a spin coater, whereby the first resist mask 14a can be formed. Two resist masks 14b. Further, for example, a dry film resist may be attached by a vacuum crimping machine or the like, and a first resist mask 14a and a second resist may be separately formed by photolithography. Mask 14b. The thickness dimension of the first resist mask 14a can be, for example, a value obtained by adding the thickness dimension of the wiring 3a to the thickness dimension of the first metal layer 3b.

The thickness dimension of the second resist mask 14b can be, for example, a value obtained by adding the thickness dimension of the third metal layer 4a to the thickness dimension of the fourth metal layer 4b.

Next, as shown in FIG. 4(c), the wiring 3a and the first metal layer 3b are sequentially formed in the opening portion of the first resist mask 14a by electroplating. Further, while the wiring 3a and the first metal layer 3b are sequentially formed, the third metal layer 4a and the fourth metal layer 4b are sequentially formed in the opening portion of the second resist mask 14b. At this time, the first seed layer 11a and the second seed layer 11b containing the conductive material reach the peripheral end of the base 2, and therefore, a current can be applied from the peripheral end of the base 2. Therefore, the wiring 3a and the first metal layer 3b, and the third metal layer 4a and the fourth metal layer 4b can be sequentially formed at a position away from the peripheral end of the base 2.

The material of the wiring 3a and the third metal layer 4a can be, for example, copper.

The material of the first metal layer 3b and the fourth metal layer 4b can be, for example, nickel or palladium.

The thickness dimension of the wiring 3a and the third metal layer 4a can be 0.02 mm or more and 0.3 mm or less.

The thickness of the first metal layer 3b and the fourth metal layer 4b may be set to be 0.003 mm or more and 0.1 mm or less.

Further, each of the first metal layer 3b and the fourth metal layer 4b may be one layer, or may be a layer in which a plurality of layers are laminated.

In addition, since a known technique can be applied to a plating solution or a process condition in a plating method, description is abbreviate|omitted.

Next, as shown in FIG. 4(d), the first resist mask 14a, the second resist mask 14b, and the remaining first seed layer 11a and the second seed layer 11b are removed.

For example, the first resist mask 14a and the second resist mask 14b can be removed by a wet ashing method.

For example, the remaining first seed layer 11a and second seed layer 11b can be removed using a wet etching method.

Next, as shown in FIG. 4(e), the second metal layer 3c is formed by covering the first metal layer 3b and the side wall 3a1 of the wiring 3a by an electroless plating method. Further, the fifth metal layer 4c is formed to cover the fourth metal layer 4b and the side wall 4a1 of the third metal layer 4a while forming the second metal layer 3c.

The material of the second metal layer 3c and the fifth metal layer 4c can be, for example, gold or palladium.

The thickness of the second metal layer 3c and the fifth metal layer 4c may be a thickness that can reliably cover the surface layer of the wiring, from the viewpoint of the functions of the second metal layer 3c and the fifth metal layer 4c. For example, the thickness dimension of the second metal layer 3c and the fifth metal layer 4c can be set to 0.0001 mm or more and 0.0003 mm or less.

Further, as shown in FIG. 2(c), each of the second metal layer 3c and the fifth metal layer 4c may be one layer, or may be a layer in which a plurality of layers are laminated.

Further, since a known technique can be applied to the plating solution or the process conditions in the electroless plating method, the description thereof will be omitted.

As described above, the wiring portion 3 and the joint portion 4 can be simultaneously formed at a position away from the peripheral end of the base portion 2.

In the method of manufacturing the wiring board 1 of the present embodiment, the wiring 3a and the first metal layer 3b, and the third metal layer 4a and the fourth metal layer 4b are formed at a position away from the peripheral end of the base 2 by a plating method.

Therefore, since the dissimilar elements which are the reducing agent components are not substantially contained in the first metal layer 3b, it is possible to suppress the formation of the enriched portion of the reducing agent component when the light-emitting element 101 is welded. As a result, the reliability associated with the joint can be improved.

Further, since the dissimilar element as the reducing agent component is not substantially contained in the fourth metal layer 4b, it is possible to suppress the enrichment portion in which the reducing agent component is formed when the other member 200 is welded. As a result, the reliability associated with the joint can be improved.

In addition, an electroless plating method is used to apply the wiring 3a and the first metal layer 3b. The second metal layer 3c is formed in a covering manner, and the fifth metal layer 4c is formed to cover the third metal layer 4a and the fourth metal layer 4b.

Therefore, even at a position away from the peripheral end of the base portion 2, the exposed portion of the wiring 3a, that is, the side wall 3a1 can be covered by the second metal layer 3c, so that the side wall 3a1 can be prevented from being corroded by oxidation or vulcanization or the like. As a result, it is possible to suppress a decrease in the reflectance of light, and it is possible to suppress a decrease in the light emission efficiency.

The embodiments of the present invention have been exemplified above, but these embodiments are presented as examples and are not intended to limit the scope of the invention. The various embodiments of the invention can be implemented in various other forms and various modifications, substitutions and changes can be made without departing from the scope of the invention. The invention or its modifications are intended to be included within the scope and spirit of the inventions Further, the respective embodiments described above can be implemented in combination with each other.

1‧‧‧Wiring substrate

2‧‧‧ base

3‧‧‧Wiring Department

3a‧‧‧Wiring

3a1‧‧‧ side wall

3b‧‧‧First metal layer

3c‧‧‧Second metal layer

4‧‧‧ joints

4a‧‧‧ third metal layer

4b‧‧‧fourth metal layer

4c‧‧‧ fifth metal layer

5‧‧‧ solder department

101‧‧‧Lighting elements

101a‧‧‧ single crystal substrate

101b‧‧ layer

101c‧‧‧Bumps

102‧‧‧wavelength conversion unit

103‧‧‧ Sealing Department

200‧‧‧ components

205‧‧‧ solder

Claims (15)

A wiring substrate (1) comprising: a base portion (2) in a flat shape; a wiring (3a) disposed on one surface of the base portion (2) and disposed away from the base portion (2) a position of the periphery; a first metal layer (3b) disposed on a side of the wiring (3a) opposite to a side of the base (2); and a second metal layer (3c) to be the first The metal layer (3b) is covered with the side wall (3a1) of the wiring (3a). The wiring substrate (1) according to claim 1, wherein a solder portion (5) containing at least tin is included on the second metal layer (3c), and the first metal layer (3b) is provided The activation energy required for the material to diffuse with the tin is higher than the activation energy required to interdif the material of the wiring (3a) with the tin. The wiring substrate (1) according to claim 1 or 2, wherein a material of the second metal layer (3c) has a higher ionization energy than a material of the wiring (3a) and the first The ionization energy of the material of the metal layer (3b). The wiring substrate (1) according to claim 1 or 2, wherein the first metal layer (3b) has a thickness larger than a thickness dimension of the second metal layer (3c). The wiring substrate (1) according to claim 1 or 2, wherein the first metal layer (3b) does not substantially contain phosphorus. The wiring board (1) according to the first or second aspect of the invention, wherein the first metal layer (3b) has a thickness of 0.003 mm or more and 0.1 mm or less. The wiring board (1) according to the first or second aspect of the invention, wherein the second metal layer (3c) has a thickness of 0.0001 mm or more and 0.0003 mm or less. The wiring substrate (1) according to the first or second aspect of the invention, wherein the first metal layer (3b) contains at least one of nickel and palladium. The wiring substrate (1) according to claim 1 or 2, wherein the first metal layer (3b) includes a plurality of layers (3b1, 3b2) laminated. The wiring substrate (1) according to claim 1 or 2, further comprising: a third metal layer (4a) disposed on the base portion (2) and provided with the wiring (3a) a side opposite to one side; a fourth metal layer (4b) disposed on a side of the third metal layer (4a) opposite to a side of the base (2); and a fifth metal layer (4c) The fourth metal layer (4b) and the sidewall (4a1) of the third metal layer (4a) are covered. The wiring substrate (1) according to claim 10, wherein the material of the wiring (3a) is the same as the material of the third metal layer (4a), and the material of the first metal layer (3b) Like the material of the fourth metal layer (4b), the material of the second metal layer (3c) is the same as the material of the fifth metal layer (4c). The wiring board (1) according to the first or second aspect of the invention, wherein the base (2) is formed of ceramic or a composite ceramic comprising ceramic and resin. A light-emitting device (100), comprising: the wiring substrate (1) according to any one of claims 1 to 4; a light emitting element (101) disposed on a side of the second metal layer (3c) opposite to a side on which the first metal layer (3b) is disposed; and a solder portion (5) disposed on the light emitting Between the element (101) and the second metal layer (3c). A method of manufacturing a wiring substrate, comprising the steps of: forming a first seed layer (11a) on one side of a base (2); forming a first resist on the first seed layer (11a) a mask (14a); in the opening portion of the first resist mask (14a), and at a position away from the periphery of the base (2), wiring (3a) and a first metal layer are sequentially formed ( 3b) removing the first resist mask (14a) and the remaining first seed layer (11a); and forming the first metal layer (3b) and the wiring (3a) a second metal layer (3c) covered by the side wall (3a1). The method of manufacturing a wiring substrate according to claim 14, wherein in the step of forming the first seed layer (11a) on one surface of the base (2), at the base (2) a surface on a side opposite to a side on which the first seed layer (11a) is formed, thereby forming a second seed layer (11b) on the first seed layer (11a) In the step of forming the first resist mask (14a), a second resist mask (14b) is further formed on the second seed layer (11b) for the first resist a step of forming the wiring (3a) and the first metal layer (3b) in an opening portion of the mask (14a) at a position away from a periphery of the base (2), in the step An opening portion of the two resist masks (14b), and away from the base (2) a position of the periphery, thereby sequentially forming a third metal layer (4a) and a fourth metal layer (4b), and the first resist mask (14a) and the remaining first seed layer (11a) In the step of removing, the second resist mask (14b) and the remaining second seed layer (11b) are further removed, and the first metal layer (3b) is formed In the step of covering the second metal layer (3c) by the sidewall (3a1) of the wiring (3a), further forming the fourth metal layer (4b) and the third metal layer (4a) The fifth metal layer (4c) covered by the side wall (4a1).